Alcoholics Anonymous (AA) is the most popular and widely accessed resource in the United States for individuals with alcohol problems (Room & Greenfield, 1993), and a variety of cross-sectional and prospective studies indicate such participation is beneficial (Emrick et al., 1993; Tonigan et al, 1995; 2002). Because AA provides direct access to a community-based recovery network available "on demand" it possesses a unique combination of accessibility, flexibility, and cost-effectiveness that makes it a valuable public health resource for addressing alcohol problems. In spite of its prevalence and salutary influence, however, knowledge about exactly why AA is helpful (i.e. the mechanisms involved), and for whom (i.e., what factors moderate benefits), remains poorly understood and rarely investigated (Kelly, 2003). One robust finding, identified across diverse [unreadable] AA-exposed alcohol dependent individuals in different trajectories of recovery, is that increased self-efficacy explains, in part, AA-related benefits (e.g, Morgenstern et al, 1997). Unclear, however, is whether increased self-efficacy, as a change mechanism, is specific to AA, and whether the relative importance of self-efficacy differs as individuals progress in recovery. [unreadable] [unreadable] The primary aims of this secondary analysis of the large, Project MATCH, prospective clinical dataset are to address these specific knowledge gaps, with the added benefit of broadening the mechanisms of change under investigation. We also investigate potential moderators of AA's effects. In so doing, we hope to begin to elucidate pathways and dynamic processes involved in recovery that will inform the timing and content of future interventions. Specifically we will: 1) examine the relative and unique contributions of four competing sets of mediational variables in explaining AA's effects- i) AA-specific variables [step work, sponsor, spirituality], ii) AA non-specific variables [self-efficacy, motivation], iii) cognitiveaffective variables (anger, depression), and, iv) social network variables [ friends' drinking]; 2) test whether the mechanisms by which AA exerts its effects vary temporally (e.g., is affect regulation more important early in recovery and spirituality more important later?); 3) assess whether AA-exposed vs. non-exposed patients tend to use different sets of mechanisms to achieve improved outcomes; and, 4) test whether certain patient subgroups benefit more or less from AA participation (e.g., patients with axis I psychopathology). A secondary aim is to examine the process and impact of AA "disaffiliation" by exploring outcomes of former AA attendees and provide information on patterns of affiliation/ disaffiliation. A further secondary aim is to investigate the relationship between AA and use of formal treatment services. Findings from this exploratory/development study will directly inform clinical interventions and provide a strong, empirical foundation from which to launch further prospective work specifically tailored to examine the broader mechanisms and processes of recovery in a mixed clinical and community sample. [unreadable] [unreadable] [unreadable]